For protection a very popular but unfortunately expensive lithium-ion/lithium-polymer rechargeable battery against over-discharge and over-current occurrence, battery and battery protector or say battery protection IC (integrated circuit) are commonly embedded into a battery pack. For malfunction such as noise issue elimination, a generally strategy for battery producer is to combine a battery protector with an internal delay circuit therein. Typically, the delay time for overcharge condition varies in a range between about 0.1-2.0 seconds.
However, to set up the parameter for overcharge condition during the testing phase, a lot of test times to find out the value are usually demanded. As a result, the total time cost is significantly increased and inferior to do tests for protection IC mass production. Furthermore, a popular protection IC is, as shown in FIG. 1, including five external pins, VCC, VSS, DOUT, COUT, Vm and an additional testing pad DS to reduce the delay time while performing wafer level test, as called CP test, for the overcharge condition search. Hence, to do a final test (FT; packed IC), it is necessary to bring the test pad out of the protection IC package according to conventional method.
An object of the present invention is to disclose a delay time control circuit for battery protection IC by using charging control pin Cout to do FT test and wafer level test without using an extra testing pad or DS pin.
Another object of the present invention is to reduce the testing time.